Hello. We have been working on a -05 petrol C4 and currently we are running into fault code C1302. The full description in Diagbox is C1302 Incoherence between the brake light switch and the pressure sensor; short circuit, short circuit to ground or open circuit
The fault can be wiped, but reappears on every engine start. Beeps, ABS light lights up and "Braking system faulty" can be seen on the screen. Looking at the live data the brake pressure is like it should be, so are the wheel sensor data. You can drive the car.
What we've done so far:
- Replaced the ABS ECU
- Replaced the ABS pump
- Tried two different brake light switches
to no avail. We are suspecting the wiring between the brake light switch and the ABS unit. How would one go about measuring / identifying any damaged wires there? Are there resources available on the wire color coding?